1. Field of the Invention
The invention relates to a feedforward amplifier and a communication equipment, which are primarily used for a base station device of mobile communication equipment.
2. Related Art of the Invention
In recent years, a high-output linear power-amplifier, compensated for distortion by a feedforward method, has been used for a base station device of mobile communication equipment.
FIG. 12 shows an example of the configuration of a conventional feedforward amplifier. In FIG. 12, reference numeral 1 denotes an input terminal, 2 an output terminal, 3 and 8 power splitters, 4 and 9 power-combiners, 5 and 13 vector adjustors, 6 a main amplifier, 7 and 10 delay circuits, and 14 an error amplifier, respectively. Further, symbols a to k and m added to the power splitters 3 and 8 and the power-combiners 4 and 9 show respective ports.
Hereinafter, the operation of the feedforward amplifier configured as described above will be described.
First, an input signal input from the input terminal 1 and including a plurality of carrier frequency components is split into two parts by the power splitter 3, and the two parts are output from the port b and port c respectively. The signal output from the port b is amplified by the main amplifier 6 through the vector adjustor 5, and then passes through the power splitter 8 and the delay circuit 10, inputting into the port j of the power-combiner 4. At this time, the signal including distortion components caused by intermodulation due to non-linearity of the main amplifier 6 in addition to the carrier frequency components are input into the port j.
Further, part of the output signal of the main amplifier 6 is took out from a port f of the power splitter 8 and input into a port h of the power-combiner 9. On the other hand, the signal output from the port c inputs into a port g of the power-combiner 9 through the delay circuit 7. Here, the vector adjustor 5 and delay circuit 7 are adjusted such that the carrier frequency components of the respective signals input into the port g and the port h may have the same amplitudes and opposite phases, thereby a signal having only the distortion components with the carrier frequency components canceled out being output from the port i.
Next, the signal output from the port i is amplified by the error amplifier 14 through the vector adjustor 13 and inputs into a port k of the power-combiner 4. Here, the vector adjustor 13 and the delay circuit 10 are adjusted such that the distortion components of signals input into the port j and port k may have the same amplitudes and opposite phases, thereby a signal having only the carrier frequency components with the distortion components canceled out being output from a port m of the power-combiner 4 to the output terminal 2.
FIGS. 13(a) to (d) shows frequency spectra of signals at the ports a, d, i and m.
As shown in FIG. 13(a), the frequency spectrum of the signal at the port a is composed of carrier frequency components. Also, as shown in FIG. 13(b), the frequency spectrum of the signal at the port d is composed of carrier frequency components and distortion components. Further, as shown in FIG. 13(c), the frequency spectrum of the signal at the port i is composed of only the distortion components with the carrier frequency components canceled out. Further, as shown in FIG. 13(d), the frequency spectrum of the signal from the port m is composed of only the carrier frequency components with the distortion components canceled out.
However, the configuration of FIG. 12 has a problem that a decrease in output power leads to a decrease in efficiency as shown in FIG. 14. Here, the efficiency means the ratio of output power to consumption power.
Further, in a base station device and the like of mobile communication equipment that uses the configuration of FIG. 12, there is a problem that when the main amplifier fails, the device can not work and thus the communication stops completely.
Considering the above problems, the invention has an object to provide a feedforward amplifier and a communication equipment of which efficiency does not decrease even in the event of the reduction of output power.
Further, the invention has another object to provide a feedforward amplifier and a communication equipment of which communication does not stop completely even in the event of the failure of the main amplifier.
One aspect of the present invention is a feedforward amplifier comprising:
a first power splitter for splitting an input signal into two parts;
a first vector adjustor for adjusting the amplitude and phase of one output signal of said first power splitter;
a main amplifier for amplifying an output signal of said first vector adjustor;
a second power splitter for splitting an output signal of said main amplifier into two parts;
a first delay circuit for delaying the other output signal of said first power splitter;
a distortion detection power-combiner for synthesizing one output signal of said second power splitter and an output signal of said first delay circuit;
a second delay circuit for delaying the other output signal of said second power splitter;
a second vector adjustor for adjusting the amplitude and phase of the output signal of said distortion detection power-combiner;
an error amplifier for amplifying the output signal of said second vector adjustor;
a distortion suppression power-combiner for synthesizing the output signal of said second delay circuit and the output signal of said error amplifier; and
control means of at least stopping the operation of said error amplifier or said main amplifier depending on a predetermined condition.
Another aspect of the present invention is the feedforward amplifier, further comprising:
first signal level detection means of detecting a first signal level that is the signal level of said input signal, or the signal level of a baseband signal in a baseband signal generating portion, or the signal level of a transmitting signal in a transmitting circuit,
wherein said predetermined condition represents said first signal level, and
when said detected first signal level is not higher than a predetermined value, said control means stops the operation of said error amplifier.
Still another aspect of the present invention is the feedforward amplifier, further comprising:
first signal level detection means of detecting a first signal level that is the signal level of a received signal in a receiving circuit,
wherein said predetermined condition represents said first signal level, and
when said detected first signal level is not lower than a predetermined value, said control means stops the operation of said error amplifier.
Yet still another aspect of the present invention is the feedforward amplifier, further comprising:
first signal level detection means of detecting a first signal level that is the signal level of said input signal, or the signal level of a baseband signal in a baseband signal generating portion, or the signal level of a transmitting signal in a transmitting circuit, or the signal level of a received signal in a receiving circuit; and
second signal level detection means of detecting a second signal level that is the signal level of said output signal,
wherein said predetermined condition represents gain of said second signal level to said first signal level, and
when said gain is out of a predetermined value, said control means stops the operation of said main amplifier.
Still yet another aspect of the present invention is the feedforward amplifier, further comprising:
first signal level detection means of detecting a first signal level that is the signal level of an input signal, or the signal level of a baseband signal in a baseband signal generating portion, or the signal level of a transmitting signal in a transmitting circuit,
wherein said predetermined condition represents said first signal level, and
when said first signal level is not higher than a predetermined value, said control means stops the operation of said main amplifier.
A further aspect of the present invention is the feedforward amplifier, further comprising:
first signal level detection means of detecting a first signal level that is the signal level of a received signal in a receiving circuit,
wherein said predetermined condition represents said first signal level, and
when said first signal level is not lower than a predetermined value, said control means stops the operation of said main amplifier.
A still further aspect of the present invention is the feedforward amplifier, wherein said distortion suppression power-combiner is a variable power-combiner that can have a tight coupling state and a loose coupling state, and
when said first signal level is higher than a predetermined value, said control means controls said variable power-combiner to have said loose coupling state, and
when said first signal level is not higher than the predetermined value, said control means controls said variable power-combiner to have said tight coupling state.
A yet further aspect of the present invention is the feedforward amplifier, wherein said distortion suppression power-combiner is a variable power-combiner that can have a tight coupling state and a loose coupling state,
when said first signal level is lower than a predetermined value, said control means controls said variable power-combiner to have said loose coupling state, and
when said first signal level is not lower than the predetermined value, said control means controls said variable power-combiner to have said tight coupling state.
A still yet further aspect of the present invention is the feedforward amplifier, wherein, when said first signal level is not higher than a predetermined value, said control means performs such control that the output signal of said error amplifier can be output without passing through said distortion suppression power-combiner.
An additional aspect of the present invention is the feedforward amplifier, wherein, when said first signal level is not lower than a predetermined value, said control means performs such control that the output signal of said error amplifier can be output without passing through said distortion suppression power-combiner.
A still additional aspect of the present invention is the feedforward amplifier, further comprising:
first signal level detection means of detecting a first signal level that is the signal level of an input signal, or the signal level of a baseband signal in a baseband signal generating portion, or the signal level of a transmitting signal in a transmitting circuit,
wherein said predetermined condition represents said first signal level, and
when said first signal level is not higher than a first predetermined value and higher than a second predetermined value that is smaller than said first predetermined value, said control means stops the operation of said error amplifier, and when said first signal level is not higher than said second predetermined value, said control means stops the operation of said main amplifier.
A yet additional aspect of the present invention is the feedforward amplifier, further comprising:
first signal level detection means of detecting a first signal level that is the signal level of a received signal in a receiving circuit,
wherein said predetermined condition represents said first signal level, and
when said first signal level is not higher than a first predetermined value and higher than a second predetermined value that is smaller than said first predetermined value, said control means stops the operation of said error amplifier, and when said first signal level is not lower than said first predetermined value, said control means stops the operation of said main amplifier.
A still yet additional aspect of the present invention is the feedforward amplifier, further comprising:
a third power splitter for splitting the output signal of said error amplifier into two parts;
a third delay circuit for delaying one output signal of said third power splitter;
a fourth power splatter for splitting the output signal of said distortion suppression power-combiner into two parts;
a fourth delay circuit for delaying one output signal of said fourth power splitter;
a second distortion detection power-combiner for synthesizing the output signal of said fourth delay circuit and the other output signal of said third power splitter;
a third vector adjustor for adjusting the amplitude and phase of the output signal of said second distortion detection power-combiner;
a second error amplifier for amplifying the output signal of said third vector adjustor;
a second distortion suppression power-combiner for synthesizing the output signal of said third delay circuit and the output signal of said second error amplifier; and
first signal level detection means of detecting a first signal level that is the signal level of said input signal, or the signal level of a baseband signal in a baseband signal generating portion, or the signal of a transmitting signal in a transmitting circuit,
wherein said control means also stops the operation of said second error amplifier depending on said predetermined condition,
said predetermined condition represents said first signal level, and
when said first signal level is higher than a predetermined value, said control means stops the operation of said second error amplifier and performs such control that the output signal of said error amplifier can not be input by said third power splitter, and performs such control that the output signal of said distortion suppression power-combiner can be output to the outside, and
when said first signal level is not higher than the predetermined value, said control means stops the operation of said main amplifier and performs such control that the output signal of said error amplifier can not be input by said distortion suppression power-combiner but can be input by said third power splitter, and performs such control that the output signal of said second distortion suppression power-combiner can be output to the outside.
A supplementary aspect of the present invention is the feedforward amplifier, further comprising:
a third power splitter for splitting the output signal of said error amplifier into two parts;
a third delay circuit for delaying one output signal of said third power splitter;
a fourth power splitter for splitting the output signal of said distortion suppression power-combiner into two parts;
a fourth delay circuit for delaying one output signal of said fourth power splitter;
a second distortion detection power-combiner for synthesizing the output signal of said fourth delay circuit and the other output signal of said third power splitter;
a third vector adjustor for adjusting the amplitude and phase of the output signal of said second distortion detection power-combiner;
a second error amplifier for amplifying the output signal of said third vector adjustor;
a second distortion suppression power-combiner for synthesizing the output signal of said third delay circuit and the output signal of said second error amplifier; and
first signal level detection means of detecting a first signal level that is the signal level of a received signal in a receiving circuit,
wherein said control means also stops the operation of said second error amplifier depending on said predetermined condition,
said predetermined condition represents said first signal level, and
when said first signal level is lower than a predetermined value, said control means stops the operation of said second error amplifier and performs such control that the output signal of said error amplifier can not be input by said third power splitter, and performs such control that the output signal of said distortion suppression power-combiner can be output to the outside, and
when said first signal level is not lower than the predetermined value, said control means stops the operation of said main amplifier and performs such control that the output signal of said error amplifier can not be input by said distortion suppression power-combiner but can be input by said third power splitter, and performs such control that the output signal of said second distortion suppression power-combiner can be output to the outside.
A still supplementary aspect of the present invention is the feedforward amplifier, further comprising:
a third power splitter for splitting the output signal of said error amplifier into two parts;
a third delay circuit for delaying one output signal of said third power splitter;
a fourth power splitter for splitting the output signal of said distortion suppression power-combiner into two parts;
a fourth delay circuit for delaying one output signal of said fourth power splitter;
a second distortion detection power-combiner for synthesizing the output signal of said fourth delay circuit and the other output signal of said third power splitter;
a third vector adjustor for adjusting the amplitude and phase of the output signal of said second distortion detection power-combiner;
a second error amplifier for amplifying the output signal of said third vector adjustor;
a second distortion suppression power-combiner for synthesizing the output signal of said third delay circuit and the output signal of said second error amplifier; and
first signal level detection means of detecting a first signal level that is the signal level of said input signal, or the signal level of a baseband signal in a baseband signal generating portion, or the signal of a transmitting signal in a transmitting circuit,
wherein said control means also stops the operation of said second error amplifier depending on said predetermined condition,
said predetermined condition represents said first signal level, and
when said first signal level is higher than a predetermined value, said control means stops the operation of said second error amplifier and performs such control that the output signal of said error amplifier can not be input by said third power splitter, and performs such control that the output signal of said distortion suppression power-combiner can be output to the outside, and
when said first signal level is not higher than the first predetermined value and higher than a second predetermined value that is smaller than said first predetermined value, said control means stops the operation of said main amplifier and performs such control that the output signal of said error amplifier can not be input by said distortion suppression power-combiner but can be input by said third power splitter, and performs such control that the output signal of said second distortion suppression power-combiner can be output to the outside, and
when said first signal level is not higher than the second predetermined value, said control means stops the operation of said error amplifier and stops the operation of said second error amplifier, and performs such control that the output signal of said distortion suppression power-combiner can be output to the outside.
A yet supplementary aspect of the present invention is the feedforward amplifier, further comprising:
a third power splitter for splitting the output signal of said error amplifier into two parts;
a third delay circuit for delaying one output signal of said third power splitter;
a fourth power splitter for splitting the output signal of said distortion suppression power-combiner into two parts;
a fourth delay circuit for delaying one output signal of said fourth power splitter;
a second distortion detection power-combiner for synthesizing the output signal of said fourth delay circuit and the other output signal of said third power splitter;
a third vector adjustor for adjusting the amplitude and phase of the output signal of said second distortion detection power-combiner;
a second error amplifier for amplifying the output signal of said third vector adjustor;
a second distortion suppression power-combiner for synthesizing the output signal of said third delay circuit and the output signal of said second error amplifier; and
first signal level detection means of detecting a first signal level that is the signal level of a received signal in a receiving circuit,
wherein said control means also stops the operation of said second error amplifier depending on said predetermined condition,
said predetermined condition represents said first signal level, and
when said first signal level is lower than a second predetermined value, said control means stops the operation of said second error amplifier and performs such control that the output signal of said error amplifier can not be input by said third power splitter, and performs such control that the output signal of said distortion suppression power-combiner can be output to the outside, and
when said first signal level is not higher than a first predetermined value that is larger than said second predetermined value and higher than said second predetermined value, said control means stops the operation of said main amplifier and performs such control that the output signal of said error amplifier can not be input by said distortion suppression power-combiner but can be input by said third power splitter, and performs such control that the output signal of said second distortion suppression power-combiner can be output to the outside, and
when said first signal level is not lower than the first predetermined value, said control means stops the operation of said error amplifier and stops the operation of said second error amplifier, and performs such control that the output signal of said distortion suppression power-combiner can be output to the outside.
A still yet supplementary aspect of the present invention is the feedforward amplifier, wherein said first signal level detection means is provided in an upstream stage of said first power splitter, or between said first power splitter and said first vector adjustor, or between said first vector adjustor and said main amplifier, or between said first power splitter and said first delay circuit, or between said first delay circuit and said distortion detection power-combiner, or at the input of said baseband signal generating portion, or at the output of said baseband signal generating portion, or in said baseband signal generating potion, or at the input of said transmitting circuit, or at the output of said transmitting circuit, or in said transmitting circuit.
Another aspect of the present invention is the feedback amplifier, wherein said first signal level detection means is provided at the input of said receiving circuit, or at the output of said receiving circuit, or in said receiving circuit.
Still another aspect of the present invention is the feedforward amplifier, wherein said second signal level detection means is provided in a downstream stage of said distortion suppression power-combiner, or between said second power splitter and said second delay circuit, or between said second delay circuit and said distortion suppression power-combiner.
Yet still another aspect of the present invention is the feedforward amplifier,
wherein said first signal level is the signal level of said input signal, and when said first signal level detection means detects the signal level of said input signal,
said first signal level detection means has a signal level detection power-splitter for splitting said input signal into two parts and detection means of detecting said signal level of one output signal of said signal level detection power-splitter, and
the other output signal of said signal level detection power splitter is supplied to a downstream stage.
Still yet another aspect of the present invention is the feedforward amplifier, wherein said second signal level detection means has a signal level detection power-splitter for splitting said output signal into two parts and detection means of detecting said signal level of one output signal of said signal level detection power-splitter, and
the other output signal of said signal level detection power-splitter is supplied to a downstream stage.
A further aspect of the present invention is the feedforward amplifier, wherein the stopping of the operation of said error amplifier is to perform such control that the power supply for said error amplifier can be turned off and/or to perform such control that the output signal of said second vector adjustor can not be input by said error amplifier.
A still further aspect of the present invention is the feedforward amplifier, wherein the stopping of the operation of said main amplifier is to perform such control that the power supply for said main amplifier can be turned off and/or to perform such control that the output signal of said first vector adjustor can not be input by said main amplifier.
A yet further aspect of the present invention is the feedforward amplifier, wherein the stopping of the operation of said second error amplifier is to perform such control that the power supply for said second error amplifier can be turned off and/or to perform such control that the output signal of said third vector adjustor can not be input by said secondary error amplifier.
A still yet further aspect of the present invention is a communication equipment comprising:
a transmitting circuit for outputting a transmitting signal from said baseband signal generated, wherein the feedforward amplifier is used for said transmitting circuit.
In the feedforward amplifier according to the invention, because the level of distortion caused by the main amplifier is low at low output power, output signals of the main amplifier are then output as-is from the output terminal of the distortion suppression power-combiner, and further the power source of the error amplifier is turned off to allow the high efficiency of the feedforward amplifier.
Further, when an abnormal event occurs in the main amplifier, the error amplifier can be used to amplify and output the input signal, thereby allowing the improved reliability of the feedforward amplifier.
Furthermore, equipping communication equipments such as mobile communication equipments with the feedforward amplifier according to the invention allows the higher efficiency and improved reliability of communication equipments such as mobile communication equipments.